1. Field of the Invention
This invention relates to continuously extruded lamina and methods of producing the same, specifically lamina having thermoplastic material on one side and fabric on the other, without use of binders, adhesives or the like to bond the thermoplastic and fabric at their interface, where these lamina can be of substantial thickness.
2. Description of the Prior Art
Lamina consisting of glass fibers on one side and plastic on the other are known, as are methods for manufacturing such lamina. A plastic-glass fiber lamina is manufactured by Symalit Lizenz A.G. in Switzerland and is available in the United States from GF Plastics Systems in Tuston, Calif. This product is generally described in Swiss patent 79-10261 assigned to Symalit Lizenz A.G.
That Swiss patent discloses pre-treating the surface of a thermoplastic, prior to application of glass material to the thermoplastic to form a lamina, by applying a volatile solvent, having between five and fifteen percent by weight of the thermoplastic dissolved therein together with dispersion colloids, and thereafter evaporating the volatile solvent so that a rough surface forms. After applying the solvent to the surface, the surface is dried with hot air to evaporate the solvent. The solvent preferably contains between about three (3.0%) and about nine (9.0%) percent by weight of the dispersion colloid, which is preferably a silicon or an aluminum compound, particularly silicon dioxide or aluminum oxide. A suitable solvent is disclosed to be DMF while the thermoplastic material is disclosed to be polyvinylidene fluoride.
The Swiss patent process is used for pre-treating the surface of the thermoplastic prior to application of a glass fiber to form a reinforced plastic layer, to provide resistance to pressure, corrosion, chemicals and high temperatures and to increase the mechanical strength of the structure.
It is also known to press fiber and molten thermoplastic together to form a fiber reinforced plastic. However, heretofore, it has only been known to do such with exceedingly thin plastic layers and thin fiber materials.